Events for human-system interaction modeling with IOPT Petri nets

In this paper, a set of event types for human-system interaction modeling is presented, and its usage with IOPT nets (Input-Output Place-Transition Petri nets) models is illustrated. Currently, a non-autonomous event based on the computation of the change with respect to a specific threshold of input signals values on two consecutive execution steps is defined for IOPT models. Other types of events are proposed, allowing the definition of an event not only based on a threshold in the signal value, but also as a change on the variation of the signal. The concept of delayed events considers two values in different time steps (other than consecutive steps). This concept can be applied to previous types of events. The concept of composed events is also introduced, in order to create events dependent on two or more events on the same signal, at the same time step as well as at different time steps. Finally, an example is used to illustrate the concepts presented.